The present invention generally relates to a sheet supplying or discharging arrangement and more particularly, to a sheet winding and discharging device provided with a pair of claw members at the periphery of a rotary drum so as to hold a sheet therebetween, and capable of automatically winding a sheet such as a paper sheet, film or the like around the rotary drum and discharging the sheet therefrom.
The sheet winding and discharging device as described above has been employed for an automatic paper feeding and discharging device in a telecopier, copying machine or the like.
In this kind of device, it is generally impossible to use a sheet longer than a predetermined length without changing the drum diameter. Therefore, there has been such a disadvantage that when the sheet which is longer than the predetermined length is erroneously wound around the drum, a sheet discharging process can not be regularly carried out even if a sheet discharging signal is generated, due to the fact that the sheet is doubly wound around the drum.
Furthermore, there has also been such a drawback that the above described device tends to be large in size, since the mechanism thereof is extremely complicated. Accordingly, the inventors of the present application have proposed a sheet winding and discharging device in Japanese Patent application No. 59-75543 which is assigned to the same assignee as the present application and discloses the above described device provided with a pair of claw members disposed at the periphery of the rotary drum for automatically winding the sheet around the drum and discharging the sheet therefrom through the opening and shutting of the claw members. The sheet winding and discharging device as described above has such an advantage that a small-sized device can be obtained owing to its extremely simple construction.
However, one of the claw members for holding the sheet therebetween has a width of approximately the same as that of the drum and the other member is also broad enough and moreover, neither thereof has any elasticity. Therefore, it has been a problem that each of the claw members has to be mounted on the drum with extremely high accuracy so as to steadily hold the sheet therebetween under relatively uniform pressure.
In addition, as shown in FIG. 1, since the distal end surface of a first claw member 5 is formed at right angles relative to the peripheral surface of the drum 2, the light emitted from the light source 7a is intercepted by the distal end portion of the first claw member 5 as indicated by dotted lines in FIG. 1 and a portion of the sheet 1 immediately below the distal end portion of the first claw member 5 is underexposed. As a result, the above described phenomenon has caused such a problem that copying noise, like a black streak, appears on a copy paper during the copying operation.